Arrangement in anode tubes for high voltage ionic valves



Feb. 23, 1960 LAMM 2,926,278

ARRANGEMENT IN ANODE TUBES FOR HIGH VOLTAGE IONIC VALVES Filed May 29,1956 2 Sheets-Sheet 1 I 30 l a 24 34 I a I L INVENTOR. U77QL 0mm Feb.23, 1960 L 2,926,278

ARRANGEMENT IN ANODE TUBES FOR HIGH VOLTAGE IONIC VALVES Filed May 29,1956 2 Sheets-Sheet 2 I N VEN TOR.

ARRANGEMENT IN ANODE TUBESFOR tuna VOLTAGE roNrc VALVES Uno Lamm,Lndv'ika, Sweden, assignor to Allmanna Svenska Elektriska Aktiebolaget,Vasteras, Sweden, a corporation of Sweden The present invention is acontinuation-in-part of my application, Serial No. 236,757, filed July14, 1951, now abandoned and relates to an anode tube for a high voltageionic valve, and particularly to a method for mounting gradingelectrodes in such a tube.

One object of the invention is to provide a construction by whichback-arcing is rendered more difficult.

Another object is to provide a construction by which the plasma layer inthe anode tube most adjacent to the surrounding insulating Wall isdivided into several electrically separated parts in order to preventbreak-down between the anode and the cathode of the ionic valve in axialdirection along the tube wall.

A further object is the provision of means for loosely supporting thegrading electrodes without attachment at the tube wall.

Although general experience shows that contacts between metallic andceramic bodies, such as porcelaintor the like, which are exposed to theconducting plasma may cause disturbances, and therefore should beavoided, it,

has been found that such contacts may be tolerated if the ionization ofthe adjacent plasma is very weak compared with that prevailing in thecurrent paths during the nonconducting intervals, and the presentinvention is based on this finding. According to the invention thegrading electrodes consist of two concentric parts, one central partprovided with a number of holes for the passage of the arc, theperipheral portion of which is so arranged that only a very smalldiffusion of ions is permitted through the interstice between twoadjacent grading electrodes, and one peripheral part forming a ringwhich rests against shoulders in the tube along practical their Wholeperiphery.

The rings resting against the shoulders may be integral with the discsin which case their introduction into the insulating tube may beeffected, for instance, while cooling down the disc to a low temperaturefor permitting the introduction of the first introduced disc past theshoulders belonging to the later introduced discs, or the discs may beintroduced past their own shoulders from beneath. As a rule it is,however, preferable to make the carrying rings loose with respect to thediscs for facilitating the introduction into the insulating .tube. Insuch case each ring may preferably be provided with a slit for beingintroduced into a groove in the wall of the anode tube. At any rate, therings should preferably be of essentially the same material as thediscs. For such material preferably pure iron may be employed. Sincethis metal has a very low elastic limit, the rings must as a rulepossess a very small radial width if they are slit at only one place andintroduced by being pressed together in analogy with, for instance,piston packing rings. It may therefore be preferable to slit them atseveral places and to join them at these places by hinge bolts. At theseslitting places it should at any rate be observed that the joints shouldnot be butt joints but should be of such a form that the passage ofpossibly leaking ions is impeded by more or less labyrinth-shapedjoints.

The contact surface between the ring and the insulating *tes Patentscreened by the edge of the insulating material lying out side it.

The bushings for admit-ting current to the grading elec trodespreferably consist of separate, conical plugs of sub stantia-lly thesame material as the tube wall, penetrating through the said wall andsealed there-against by a glaze layer. As these plugs may be turned orground and as the holes may be bored, a finer precision of the placingof said plugs can be obtained than when using perforated projections,which are formed in advance, as has been previously proposed.

Outside the outer end of the plug there is placed a metal cap known perse, and this cap is provided at the inside with a central extension ofsubstantially the same material, said extension traversing a hole in theplug and serving for the introduction of current. The sealing of thesaid cap to the plug may be effected before, simultaneously with orafter the sealing of the plug into the tube Wall.

The central leading-in conductor is preferably tubular in order tofacilitate the connection to thepotential distributor in the manner tobe described more in detail below.

It should either have a smaller outer diameter than the diameter of theplug hole or terminate at a certain distance inside the inner end of theplug, in order that a possible contact between the metal and theinsulating wall shall be well screened in relation to the active partsofthe in;

terior of the anode tube.

7 By the precision obtained in a leading-in bushingthe type nowdescribed, the use of a very she-rt flexible conductor for connecting tothe corresponding voltage distributor is permitted, it being possible toscreen the said 7 conductor as well as the leading-in conductor. The.

former may, for instance, take the form of a contact brush composed of aplurality of Wires, which is introduced into the hollow conductor.Possibly a brushshaped conductor may instead be secured tothe cap andbetween a grading electrode and the insulating Wall. Fig.

3 shows in a plan view a joint of a divided ring and Fig.

4 is a corresponding side view. Fig. 5 shows a side viewand Fig. 6 across section of the ring at the place of aof bayonet joint. Fig. 7shows a detail sectionm view a leading-in bushing for the discs. I Inthe form shown in Fig. 1, the anode tube 3 has a number of identicalgrading electrodes 19 containedtherein, each of said electrodescomprising a central part 26 and a peripheral part 1; The central partof the grading electrodes may for instance consist of a centralbox-shaped construction 27 provided with a number of holes 28 for'thepassage of the arc and an outer single portion 29 of conical shapeending with a bent portion 30 which is joined with the outer part1. Saidouterpart 1 may consist of a ring preferably made from-the same materialas the central part 26 and either being in one piece or in severalpieces which may be joined together. The conical portion 29 of thecentral part 26 should have such an extension that the intersticesagainst adjacent electrodes have a length which is many times the spacebetween adjacent electrodes for the purpose of preventing diffusion ofions from the central portion of the part 26 to the inner periphery ofthe anode tube 3. Along the anode tube a resistor 20 is shown which hasone of its ends connected to the anode bolt 21 which is PatentedFeh- 23,

Of course other connected to the anode body 31 by means of a conductor32 and a screw 33, while the other end of the resistor is intended to beconnected to the cathode of the ionic valve, not shown. The resistor 20serves as the potential distributor while leads 22 and 23 connecttappings on said resistor with the cap 14 and 14'', respectively of theleading-in conductors for the grading electrodes. As these leading-inconductors are divided around the circumference of the anode tube asshown in the left hand half of the figure, only two of such conductorsare shown on the right hand portion of the drawing. The bottomleading-in conductor 24 is intended to be connected to a grid controldevice as it belongs to the grid 25 of the tube, said grid is preferablymounted according to the same principle as the grading electrodes 26 andfor this purpose a ring 34 is shown to be inserted in a peripheralgroove. The anode tube is joined with the portion 35 of the ionic valvevessel.

From the enlargement, shown in Fig. 2, it will be clear that the ring 1rests in a groove at the inside of the insulating anode tube 3 and thatthe borders of the grooves form shoulders 2 at the inside surface.Preferably the grooves are ground into the insulating wall for effectingthe necessary precision and the shoulders serve for reinforcing thiswall. The ring is, on the other hand, preferably provided with acircumferential recess 4 which leaves the inner edge of the shoulder inthe insulating wall 3 free and to a certain extent screens the innerlimiting line for the bearing of the ring against the insulating wall.Especially if the height of the ring is equal to the height of thegroove in the insulating wall so that the ring will rest against theinsulating material at the upper side, this upper side of the ringpreferably is provided with a corresponding recess for the same purpose.

If the ring is sufficiently elastic to be bent inwardly and then expandagain, so as to fit into the groove in the insulating wall, it may besufiicient to slit it at one place. If it is made from pure iron, itselasticity is usually insufiicient for the above purpose, and the ringmust be cut into several portions of equal or unequal length and saidportions are preferably joined together by hinges at all places but one.Fig. 3 shows such a hinge joint in plan view and Fig. 4 the same jointin a side view in the most simple arrangement having oblique jointsurfaces, but the surfaces may of course also be graduated or shaped inanother manner. The hinge bolt is designated by 6. At one place thesections should be free from each other during the introduction, butthey may preferably be joined there by a bolt after the introduction.

After the ring has been put in place the inner part of the gradingelectrode is introduced, only the peripheral portion ofsaid inner partbeing shown in Figs. 2, 6, 7, and the inner part is secured to the ringpreferably only at a small number of places, for instance, by some kindof bayonet joint. Fig. 5 shows the slot in the ring serving this purposeas seen from its inside, and Fig. 6 shows a corresponding cross section.The slot in the ring consists of an axially extending portion 7, whichserves to admit the pin 9 extending'from the inner part 18 which shouldpass the aforesaid ring to be secured into another ring. Theslot hasfurther an off-set portion 8, through which the pin belonging to thegradingelectrode which the said ring shall form a part of shall beintroduced from the side, whereupon it should pass into the 4 lowestportion of the off-set slot and rest there, the pin and slot thereforming a bayonet joint.

In Fig. 7 the tube wall 3 is provided with a conical hole into which aconical plug 12, preferably of the same material as the tube wall 3 isinserted and sealed by a glaze. This plug has a penetrating hole 13,which however, at the outer end of the plug is covered by a cap 14sealed by glaze. The cap carries a tubular conductor 15, whichpreferably runs freely through the hole 13 of the plug and into saidconductor 15 there may be intro duced an elastic, preferablybrush-shaped contact 16, which may be screwed into a part 17 secured tothe inner part of a grading electrode 18 after part 17 has been securedin place. As aforesaid, several other elastic contact types may beemployed. Characteristic to the arrangement is that in any case, onaccount of the precision of the position of the bushing, no longflexible conductor is needed for the connection. Instead of a glaze,other sealing means may be employed, for instance a lacquer.

I claim as my invention:

1. In an anode tube for high voltage ionic valves a continuousinsulating wall of ceramic material, an anode body, a number ofsimilarly shaped and positioned grading electrodes, means to keep saidelectrodes continuously under different potentials, said electrodes eachconsisting of two parts, one central part, means for the detachableconnection of the said central part to the said peripheral part and oneperipheral part, said central part being provided with holes for thepassage of the arc, the outer portion of said central part havingconical shape so that it forms, with the corresponding parts of adjacentelectrodes, interstices having lengths many times the space between twoadjacent conical parts, said peripheral part forming a ring, andperipheral grooves accommodating said peripheral ring parts andlimited-by shoulders in the inner surface of said insulating wall to anumber of grooves corresponding to the number of the grading electrodes.

2. Grading electrodes according to claim 1 comprising detachable jointsbetween their central part and their peripheral part for the attachmentof the said central parts to the said peripheral parts after theassembly of the peripheral parts on the said shoulders on the internalsurface of the insulating wall.

3. Grading electrodes according to claim 1 in which the peripheral partsconsist of rings, each split at at least two points along theirperiphery.

4. In an anode tube according to claim 1 said means to keep the gradingelectrodes under different potentials, consisting of a potential dividerconnected between anode and cathode potential, plugs of insulatingmaterial penetrating through said insulating wall, caps sealing holesthrough said plugs at their outer ends and leading-in conductors forsaid grading electrodes contained in said holes, leads connectingtappings on said potential divider with said caps.

References Cited in the file of this patent 'UNITED STATES PATENTS2,182,185 Trump Dec. 5, 1939 2,446,600 Lamm Aug. 10, 1948 2,629,066Eitel Feb. 17, 1953 2,812,466 Murdock Nov. 5, 1957 UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent N00 2,926 278 February 23 1960Uno Lamm It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 4, line 29 strike out "and one peripheral part" and insert thesame after "part" in line 27, same column,

Signed and sealed this 6th day of September 1960 SEAL) Atest:

ERNEST W, SWIDER ROBERT C. WATSON Afiesting Officer Commissioner ofPatents

